/ Advice on child support (Irish with my Polish husband)
And presumably spend any money he might have on the move, right? That's a very smart suggestion. :-/
In the current economic climate the most one can do is try to keep the job they do have. Also, if he pays 350 PLN the ex-wife should pay the same, I think spending 700 PLN a month in total on a child under 10 is more than enough.
It doesn't work like that.
If they shared childcare 50-50, than yes, they should be spending an equal amount of money each. But here, because the ex wife is putting in hours actually spent on bringing up the child, he has to pay more money than her. I think anything less than 500zł a month is ridiculous.
Also, from what I can see, the ex wife was not "money crazy", as the OP put it, before they lowered the payment to 150zł per month, which is just insulting. Also, it's illegal, you can't just decide that from now on you're paying less without the court order.
The fact she lives with her parents is neither here nor there, none of the OP's business. Life in a village is not that much cheaper than in the city - you don't have Tesco there with own brands, village shops may be quite expensive. And the fact that the OP doesn't take her kids to the zoo, cinema or swiming pool is her own problem. As far as I'm concerned, if you can't afford children, you shouldn't have them.